Indocyanine green (ICG) is a well-known fluorsecent dye. The dye is presently marketed by Akorn, Inc. (Buffalo Grove, Ill.) under the trademark IC GREEN™. ICG is presently supplied as a lyophilized powder (25 mg) for reconstitution with 5 ml sterile water for injection (WFI), or for reconstitution at 20 mg/ml in WFI. The reconstituted ICG composition (at 5 mg/ml) should be used within 10 hours, with any unused portion being discarded.
The U.S. Food and Drug Administration has approved this dye as an injectable drug for use in determining hepatic function, cadiac output and liver blood flow, as well as for opthalmic angiography. In opthalimic angiography, the ICG is excited to fluorescence by radiation, permitting angiograms of the opthalmic vasculature to be obtained.
Although currently available aqueous ICG compositions provide adequate levels of ICG for use in the approved indications, the solubility of ICG in WFI decreases as the concentration exceeds 5 mg/ml. Thus, a need exists for an aqueous ICG composition that exhibits beneficial properties exceeding those possessed by the currently approved compositions, particularly with respect to enhancements in ICG concentration and stability.